(Corrects day of the week in first paragraph to Wednesday from Tuesday)

TORONTO, June 19 (Reuters) - BlackBerry shares fell 4 percent on Wednesday after a Bernstein Research analyst cut his rating on the stock to “underperform” ahead of the company’s quarterly earnings release next week.

While Bernstein’s Pierre Ferragu said he expected disappointing results from the smartphone maker, other analysts have bullish expectations, pointing to an even more volatile run for a generally volatile stock.

In the last few days, there have been are both upgrades and downgrades to the stock as BlackBerry seeks to win back market share it has lost to the likes of Apple Inc and Samsung Electronics with new smartphones powered by its BlackBerry 10 operating system.

“The initial enthusiasm that we observed for Blackberry 10 devices now appears to be waning,” Ferragu said in a note to clients. He also cut his price target on the company to $10 from $15.

Shares of BlackBerry, which reports fiscal first-quarter results on June 28, fell 3.6 percent to $14.31 in morning Nasdaq trading. The stock dropped as low as $6.22 last September, but has more than doubled in value since then.

The new devices launched over the last few months to mostly positive reviews. But the company has not yet released too many details about sales figures.

Societe Generale analyst Andy Perkins last week upgraded BlackBerry to “buy” from “sell,” saying that channel checks had come up with some surprisingly strong numbers for the company’s unit sales.

RBC Capital Markets on Monday raised its first-quarter sales estimate to 3.5 million BlackBerry 10 units from 2.75 million. It expects shipments of 4 million BB10-enabled devices in the current quarter, up from a prior outlook of 3 million. (Reporting by Euan Rocha; Editing by Lisa Von Ahn)